Glued-in corner posts are a structural feature of corrugated cartons or trays designed for vertical stacking. The laminated corner posts are capable of supporting substantial vertical loads beyond those conventionally accommodated by normal cartons or trays. Because the folding of the corner structures requires multiple and progressive steps, this action has previously been accomplished at successive machine stations during intermittent movement of the carton blanks along a conveyor system. This intermittent movement of the carton blanks limits the operational speed of such machinery.
The basic object of the present disclosure is to present a machine and method for progressively folding such corner structures during continuous movememt of blanks from a supply hopper to conventional forming dies at which the carton or tray is erected. Another purpose is to form each corner post by using conical roller surfaces capable of accurately locating and pressing against the significant edges and corner surfaces involved in such laminated corner structures. The continuous operation of the disclosed folding system achieves volume results and speeds impossible in an intermittently operated system.